If the world could vote on 6 November, Barack Obama would win by a landslide. A global poll for the BBC World Service revealed that 20 out of 21 countries preferred the president to his challenger. But when you watched the presidential debate on foreign policy on Monday night you had to wonder why. Not because Mitt Romney was better, but because on matters of policy, Obama was almost as bad. It takes a friend to reveal the harsh truth to the global community, so here it is: "Obama's just not that into you."

No one could love Israel more, care less about the Palestinians, put more pressure on Iran or be a greater fan of drone attacks or invading Libya. Both candidates agreed that America's task was to spread freedom around the world: nobody mentioned Guantánamo Bay, Abu Ghraib or rendition. "Governor, you're saying the same things as us, but you'd say them louder," said Obama. It was a good line. The trouble was it condemned them both.

It was one of many lines Obama delivered that sought not just to correct Romney but belittle him. "When it comes to our foreign policy, you seem to want to import the foreign policies of the 1980s, just like the social policies of the 1950s and the economic policies of the 1920s."

When Romney complained that America had fewer ships in the US navy than in 1916, Obama answered: "We also have fewer horses and bayonets."

Obama's task was to cast his opponent as an opportunist out of his depth, not waving at the electorate but drowning before them. Promising to be "strong and steady not wrong and reckless," he painted Romney at every opportunity as a flip-flopper.

Romney had a tougher task. With the race tightening and just two weeks to go until polling day, he had to focus the national imagination on the prospect of a President Romney. His problem was that Obama had left no room to the right on foreign policy that would not have left Romney sounding like Herman Cain (who would probably bomb Ubeki-beki-beki-beki-stan-stan if only he had known where it was).

So after a month of shape-shifting, fact-mangling and question-dodging Romney finally morphed into a peacenik. "But we can't kill our way out of this mess," he said, with a plausibility that would have had him booed off stage in a Republican primary.

He spoke of promoting peace and democracy as though that had been the idea all along, and America's benevolent instincts had been blown off course by some freak wind. He parried Obama's slights as though they were beneath him. "Attacking me is not an agenda," was one retort. "I've got a policy for the future," was another.

But there are only so many times you can shake an Etch A Sketch before its capacity to form an image starts to falter. Romney was less than convincing. And while Obama's put-downs were well-rehearsed, they also worked. He came out on top although it's difficult to imagine he changed any minds or converted any waverers.

Both men, when given half a chance, tried to steer the debate back to the central issue in the election – the economy. Viewers could be forgiven for thinking the answers to issues relating to Iran, Afghanistan, the Middle East, Iraq or China were Obamacare, educational reform, tax rates and loopholes.

This was the last set-piece of the campaign. After the primaries, conventions and two previous debates, all that's left now are doors to knock, phones to ring and rallies to attend. On the ground and in the heartland there is still everything to play for. But from the podiums and the spin rooms the campaign has played itself out.